`Viewer` output missing horizontal line after header

[edelarua]

As described below, the horizontal line following the header in rtable objects that is included in the ASCII output is not included in the Viewer output, or as_html output.

Observed that the ASCII output includes horizontal line displayed between header and body but using Viewer() does not display the line.

ASCII

Viewer()

Was thinking that the hline might also be missing in teal output since Viewer() is also html. this is admittedly trivial. ;-)

Originally posted by @npaszty in insightsengineering/chevron#385 (comment)

[gmbecker]

I believe the initial design intent is that the horizontal line is not needed because the header space is differentiated by color and bolding @edelarua @npaszty

That said I don't really feel strongly about this one way or another and honestly have not done much at all to the HTML rendering logic in my multiple years on the project.

[npaszty]

@gmbecker
this was feedback to dev team from a chevron template UAT.
when I described as trivial that was directed at level of importance not as to whether it is a trivial fix. ;-).
so for my part it is definitely a backlog item.